1. Field of the Invention
This invention relates in a general manner to the field of fault location in signal transmission systems. More particularly, the invention relates to loop-back devices for fault locating in line equipments included in half-duplex optical transmission systems.
The conventional way to locate operating faults in transmission systems is to selectively set up loop-back paths between inputs and outputs of equipments included in said system. In conventional line terminal equipments connected to metallic-type transmission media, different components are available and can be used, such as e.g. electromagnetic microrelays or switching members in the solid state. In the case of an optical-type equipment, the use of an optical switch would simplify the design of a loop-back device. However, optical switches are only available at present at the laboratory stage and are not marketed.